1. Field of the Invention
The invention relates to a vehicle gear shift control device and a gear shift control method applied to a transmission that is provided in a vehicle equipped with an internal combustion engine and is configured to be capable of shifting a plurality of gears having mutually different gear ratios.
2. Description of the Related Art
A conventional vehicle gear shift control device controls an automatic transmission having six forward gears based on shift maps in which shift lines are set for each shift pattern of the gears (see, for example, Japanese Patent Application Publication No. 2003-322249 (JP-A-2003-322249)).
In the drive device of JP-A-2003-322249, in the case of having set the smallest sixth gear of a gear ratio (rotating speed of the input shaft of a transmission/rotating speed of the output shaft of a transmission) to an even smaller gear ratio in order to improve fuel efficiency, at high speeds exceeding the vehicle speed suitable for the sixth gear, the operating point intersecting with the optimum engine line is located at a lower gear than the sixth gear. Consequently, an optimum gear ratio that improves fuel efficiency is not attained by the sixth gear at such high speeds, thereby resulting in the possibility of degrading fuel efficiency if the transmission continues to operate in the sixth gear.